Abstract:
In order to solve the problem of high price and poor size controllability of rare earth doped upconversion luminescent materials, spherical SiO
2@Gd
2O
3:Yb
3+, Ln
3+ (Ln=Er, Tm, Ho) core-shell upconversion luminescent materials were successfully synthesized by simple chemical precipitation method using low cost and easy to prepare SiO
2 microspheres as cores and uniformly coated with Gd
2O
3:Yb
3+, Ln
3+ (Ln=Er, Tm, Ho) shells. XRD results show that the SiO
2@Gd(OH)CO
3:Yb
3+, Ln
3+ precursor is firstly obtained by the reaction of urea with rare earth ions, then the Gd(OH)CO
3:Yb
3+, Ln
3+ shell is further transformed into cubic phase Gd
2O
3:Yb
3+, Ln
3+ with good crystallinity after calcination at 800℃. SEM and size distribution images show that the prepared samples are ideal core-shell microspheres with uniform size, and the average diameter is about 580 nm. Under the excitation of 980 nm, SiO
2@Gd
2O
3:Yb
3+, Ln
3+ (Ln=Er, Tm, Ho) core-shell microspheres exhibit red, blue and green emissions respectively, corresponding to the
4F
9/2→
4I
15/2 transition of Er
3+, the
1G
4→
3H
6 transition of Tm
3+, and the
5S
2→
5I
8 transition of Ho
3+, which are consistent with the luminescence color region of chromaticity color coordinates, indicating that three color upconversion luminescence is successfully achieved by simply adjusting the doped rare-earth ion species in the shell of SiO
2@Gd
2O
3:Yb
3+, Ln
3+ core-shell microspheres.